Ok, I know that this is a common question already adressed in other threads but please let me add some context:

I'm working on a server-client apllication which provides a CLI, I need two instances of this application working first instance acts as server and second instance acts as backup server; both servers are connected through a TCP sockets. In certain situations the role of server and backup server can swap, this can happen writting a swap instruction on the CLI.

I'm connecting to the CLI using PuTTY. The PuTTY instance is opened inside the application with a call to CreateProcess:

STARTUPINFO si = { sizeof(STARTUPINFO) };

// ...

process_information = PROCESS_INFORMATION();

BOOL success = CreateProcess
(
    NULL,
    command, // putty.exe param1 param2
    NULL,
    NULL,
    TRUE,
    DETACHED_PROCESS,
    NULL,
    static_cast<LPCWSTR>(workingDirectory),
    &si,
    &process_information
);

Doing this call the PuTTY process appears as child of my application process both on task manager and Process Explorer.

But I have a problem with this approach: for some unknown reason if the PuTTY console is open when the server becomes backup server it maintains the TCP listener open and after swapping again it creates a new listener on the same port, then the backup server connects to the previous TCP listener which is not managed by the application anymore.

Here is the catch:

• If I close the PuTTY console the zombie TCP listener closes and then the connection is stablished with the correct listener.
• If I open the PuTTY console manually (instead of calling CreateProcess from inside my application) the TCP listener closes propperly and swapping server roles works perfectly.

Until I figure out why opening the PuTTY instance from CreateProccess makes my TCP connections behave this way I want to open the PuTTY as if it was NOT opened from within my application.

What I've tried so far:

1. Create a batch file that calls PuTTY and CreateProcess the batch file (failed).
2. Create a job with CreateJobObject and assign the PuTTY process to that job (failed).

The reason behind the #1 try is that I've read that you can create a process (A) that creates a second process (B) and then finishing the first process (A) leaves it orpah, but I wasn't able to make the batch file run at all.

Any help is appreciated, thanks for your time.

CodePudding user response：

ShellExecute, ShellExecuteEx should do what you want, they don't create parent-child relationships between precesses.